An alarm clock is a clock that is designed to make a loud sound at a specific time. The primary use of these clocks is to awaken people from their sleep in order to start their days in the mornings, but can also be used for short naps; they are sometimes used for other reminders as well. To stop the sound, a button or handle on the clock needs to be pressed, and some stop automatically after a few minutes if left unattended. A classical analog alarm clock has an extra hand that is used to specify the time at which to activate the alarm.
Traditional mechanical alarm clocks have one or two bells that ring, but digital alarm clocks can make other noises. Simple battery-powered alarm clocks make a loud buzzing sound, or other similar noise to wake a sleeper, while novelty alarm clocks can speak, laugh, or sing. Some alarm clocks have radios that start playing at specified times, and are known as clock radios. A progressive alarm clock, still new in the market, can have different alarms for different times (see Next-Generation Alarms).
In a mechanical bell-style alarm clock, a mainspring drives a gear that propels a clacker back and forth between two bells or between the sides inside a single bell. In an electric bell-style alarm clock, the bell rings with an electromagnetic circuit and armature that turns the circuit on and off again repeatedly.
In China, a striking clock was devised by the Buddhist monk and inventor Yi Xing (683-727). The Chinese engineers Zhang Sixun and Su Song integrated striking clock mechanisms in astronomical clocks in the 10th and 11th centuries, respectively. A striking clock outside of China was the water-powered clock tower near the Umayyad Mosque in Damascus, Syria, which struck once every hour. It was constructed by the Arab engineer al-Kaysarani in 1154.
From the 14th century, some clock towers in Western Europe were also capable of chiming at a fixed time everyday, the earliest of which was described by the Florentine writer Dante Alighieri in 1319. The most famous original striking clock tower still standing is possibly the one in St Mark's Clocktower in St Mark's Square, Venice. The St Mark's Clock was assembled in 1493, by the famous clockmaker Gian Carlo Rainieri from Reggio Emilia, where his father Gian Paolo Rainieri had already constructed another famous device in 1481. In 1497, Simone Campanato moulded the great bell (h. 1,56 m., diameter m. 1,27), which was put on the top of the tower where it's alternatively beaten by the Due Mori (Two Moors), two bronze statues (h. 2,60) handling a hamme.
A clock is the alarm clock that runs away and hides when you don't wake up. Clock gives you one chance to get up. but if you snooze, Clock will jump off of your nightstand and wheel around your room looking for a place to hide. No kidding. Clock is much like a misbehaving pet, only he'll get up at the right time. When the alarm sounds, Clock will start beeping. You can snooze once for your chosen number of snooze minutes and if you don't get up, Clock will start beeping again and run away. If 0 was chosen as the snooze time, Clock will run away as soon as the alarm sounds. He always starts by moving forward off of your nightstand. Then he will move around for 30 seconds in different directions.
Do you have a hard time getting out of bed in the morning? If so, then "Clocky" the alarm clock may be the solution for you. When Clocky's "snooze" button is pushed, it rolls off of your nightstand like a frantic robot (R2-D2 comes to mind), chirping, beeping, rolling in random directions on the floor and spinning in circles until you catch up with it and turn the alarm off.
A less-polished version of Clocky (covered by shag carpet) was originally invented in 2004 as a class project by former Massachusetts Institute of Technology graduate student Gauri Nanda, who was inspired to create Clocky after being woken up repeatedly by kittens nibbling at her toes to get her out of bed. Although she never anticipated that Clocky would suddenly become so popular in the blogosphere and in the mainstream press, after graduating from MIT she formed a company named Nanda Home, which since 2006 has sold the Clocky models (among other technology products) that are now available commercially.